A term used by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) to describe a serious medical error, including medication errors with serious consequences, suicide, unauthorized departure, wrong-site or wrong-patient surgery, intrapartum maternal death, violent crime committed against a patient, severe patient fall, or hemolytic blood transfusion. For more information, visit the JCAHO web site.

An unexpected occurrence involving death or serious physical or psychological injury, or the risk thereof. Serious injury specifically includes loss of limb or function. The phrase, "or the risk thereof" includes any process variation for which a recurrence would carry a significant chance of a serious adverse outcome. Such events are called "sentinel" because they signal the need for immediate investigation and response.

Adverse health events that may have been avoided through appropriate care or alternate interventions. Providers are required to alert JCAHO and often state licensing authorities of all sentinel events, including a review of risk factors, preventative measures and case analysis.

A sentinel event is defined by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) as any unanticipated event in a healthcare setting resulting in death or serious physical or psychological injury to a person or persons, not related to the natural course of the patient's illness. Sentinel events specifically include loss of a limb or gross motor function, and any event for which a recurrence would carry a risk of a serious adverse outcome. Sentinel events are identified under JCAHO accreditation policies to help aid in root cause analysis and to assist in development of preventative measures.